There is a fundamental tension in space exploration that has created ongoing debates for decades. By creating the infrastructure we need to explore other worlds, we damage them in some way, making them either less scientifically interesting or less pristine, which some would argue, in itself, is a bad thing. A new paper available in JGR Planets, from Francisca Paiva, a physicist at Instituto Superior Tcnico, and Silvio Sinibaldi, the European Space Agencys (ESAs) planetary protection officer, argues that, in the Moons case at least, the problem is even worse than we originally thought.